RESUMEN
Fungal communities (the mycobiota) are an integral part of the gut microbiota, and the disruption of their integrity contributes to local and gut-distal pathologies. Yet, the mechanisms by which intestinal fungi promote homeostasis remain unclear. We characterized the mycobiota biogeography along the gastrointestinal tract and identified a subset of fungi associated with the intestinal mucosa of mice and humans. Mucosa-associated fungi (MAF) reinforced intestinal epithelial function and protected mice against intestinal injury and bacterial infection. Notably, intestinal colonization with a defined consortium of MAF promoted social behavior in mice. The gut-local effects on barrier function were dependent on IL-22 production by CD4+ T helper cells, whereas the effects on social behavior were mediated through IL-17R-dependent signaling in neurons. Thus, the spatial organization of the gut mycobiota is associated with host-protective immunity and epithelial barrier function and might be a driver of the neuroimmune modulation of mouse behavior through complementary Type 17 immune mechanisms.
Asunto(s)
Microbioma Gastrointestinal , Micobioma , Receptores de Interleucina-17/metabolismo , Conducta Social , Animales , Hongos , Inmunidad Mucosa , Mucosa Intestinal , Ratones , Membrana MucosaRESUMEN
Economic biowaste to biofuels production technology suffers from issues including high production cost of cellulase enzyme and its low efficiency. In this study five lignocellulosic biomass based on their high cellulosic contents are employed in 1:1 ratio with mixed fungal consortia to achieve enhance cellulase production via solid state fermentation. Under the optimum condition total 41 IU/gds FP activity was achieved in 120 h at 40 °C and pH 6.0. Further, crude cellulase was evaluated to improve thermal and pH stability under the influence of 2.0 mg/L NiFe2O4 nanoparticles, showed stability at 70 °C and pH 6.0 up to 8 h. Consequently, NiFe2O4 nanoparticles treated cellulase was used for the enzymatic hydrolysis of alkali treated wheat straw, and total 53 g/L reducing sugars could be produced in 18 h at 65 °C and pH 6.0. Thus, nanoparticles mediated enzymatic hydrolysis exhibited â¼ 29% and â¼ 28% higher sugar yield and productivity as compared to control after 18 h.
Asunto(s)
Celulasa , Nanopartículas , Biomasa , Celulasa/metabolismo , Fermentación , Hidrólisis , Lignina , Triticum/metabolismoRESUMEN
In this study, we examined a synthetic microbial consortium, composed of two selected bacteria, i.e., Citrobacter freundii so4 and Sphingobacterium multivorum w15, next to the fungus Coniochaeta sp. 2T2.1, with respect to their fate and roles in the degradation of wheat straw (WS). A special focus was placed on the effects of pH (7.2, 6.2, or 5.2), temperature (25 versus 28 °C), and shaking speed (60 versus 180 rpm). Coniochaeta sp. 2T2.1 consistently had a key role in the degradation process, with the two bacteria having additional roles. Whereas temperature exerted only minor effects on the degradation, pH and shaking speed were key determinants of both organismal growth and WS degradation levels. In detail, the three-partner degrader consortium showed significantly higher WS degradation values at pH 6.2 and 5.2 than at pH 7.2. Moreover, the two bacteria revealed up to tenfold enhanced final cell densities (ranging from log8.0 to log9.0 colony forming unit (CFU)/mL) in the presence of Coniochaeta sp. 2T2.1 than when growing alone or in a bacterial bi-culture, regardless of pH range or shaking speed. Conversely, at 180 rpm, fungal growth was clearly suppressed by the presence of the bacteria at pH 5.2 and pH 6.2, but not at pH 7.2. In contrast, at 60 rpm, the presence of the bacteria fostered fungal growth. In these latter cultures, oxygen levels were significantly lowered as compared to the maximal levels found at 180 rpm (about 5.67 mg/L, ~ 62% of saturation). Conspicuous effects on biomass appearance pointed to a fungal biofilm-modulating role of the bacteria.Key points⢠Coniochaeta sp. 2T2.1 has a key role in wheat straw (WS) degradation.⢠Bacterial impact shifts when conditions change.⢠pH and shaking speed are key drivers of the growth dynamics and WS degradation.
Asunto(s)
Ascomicetos , Consorcios Microbianos , Lignina , SphingobacteriumRESUMEN
The microbial degradation of plant-derived compounds under salinity stress remains largely underexplored. The pretreatment of lignocellulose material, which is often needed to improve the production of lignocellulose monomers, leads to high salt levels, generating a saline environment that raises technical considerations that influence subsequent downstream processes. Here, we constructed halotolerant lignocellulose degrading microbial consortia by enriching a salt marsh soil microbiome on a recalcitrant carbon and energy source, i.e., wheat straw. The consortia were obtained after six cycles of growth on fresh substrate (adaptation phase), which was followed by four cycles on pre-digested (highly-recalcitrant) substrate (stabilization phase). The data indicated that typical salt-tolerant bacteria made up a large part of the selected consortia. These were "trained" to progressively perform better on fresh substrate, but a shift was observed when highly recalcitrant substrate was used. The most dominant bacteria in the consortia were Joostella marina, Flavobacterium beibuense, Algoriphagus ratkowskyi, Pseudomonas putida, and Halomonas meridiana. Interestingly, fungi were sparsely present and negatively affected by the change in the substrate composition. Sarocladium strictum was the single fungal strain recovered at the end of the adaptation phase, whereas it was deselected by the presence of recalcitrant substrate. Consortia selected in the latter substrate presented higher cellulose and lignin degradation than consortia selected on fresh substrate, indicating a specialization in transforming the recalcitrant regions of the substrate. Moreover, our results indicate that bacteria have a prime role in the degradation of recalcitrant lignocellulose under saline conditions, as compared to fungi. The final consortia constitute an interesting source of lignocellulolytic haloenzymes that can be used to increase the efficiency of the degradation process, while decreasing the associated costs.
Asunto(s)
Bacterias/metabolismo , Biomasa , Hongos/metabolismo , Lignina/metabolismo , Consorcios Microbianos , Triticum/metabolismo , Bacterias/clasificación , Bacterias/aislamiento & purificación , Hongos/clasificación , Hongos/aislamiento & purificación , Hidrólisis , Salinidad , Microbiología del SueloRESUMEN
AIM: The aim of this study was to develop and evaluate bacterial-fungal communities to deconstruct switchgrass to biofuel precursors. METHODS AND RESULTS: Bacterial-fungal consortia, mesophilic (25°C) and thermophilic (50°C), were enriched from switchgrass bales from which enzyme mixtures were used to deconstruct delignified switchgrass (DSG). The bacterial-fungal consortia were able to produce enzymes including endoglucanase, exoglucanase, ß-glucosidase, xylanase, xylosidase and pectinase to convert DSG to soluble carbohydrates. 454 pyrosequencing revealed that Paenibacillus and Streptomyces were the dominant bacteria in the mesophilic and thermophilic consortia respectively. Penicillium and Acremonium were the dominant fungi in the mesophilic consortia, whereas Aspergillus and Penicillium were the dominant fungi present in the thermophilic consortia. CONCLUSIONS: The results show that the state of cultivation, solid-state or submerged-state, affects the community structure as well as enzyme activities produced by these bacterial-fungal consortia. The enzyme mixture produced by the bacterial-fungal consortia released a higher amount of xylose than glucose during saccharification of DSG. SIGNIFICANCE AND IMPACT OF THE STUDY: The study provides a novel approach to produce enzymes for conversion of lignocellulolytic feedstocks to soluble sugars which can be used to produce biofuel precursors.
Asunto(s)
Bacterias/enzimología , Biocombustibles , Metabolismo de los Hidratos de Carbono , Hongos/enzimología , Panicum/metabolismo , Amoníaco/metabolismo , Consorcios Microbianos , Panicum/microbiología , Xilosa/metabolismoRESUMEN
The mixed microbial communities that occur naturally on lignocellulosic feedstocks can provide feedstock-specific enzyme mixtures to saccharify lignocelluloses. Bacterial-fungal communities were enriched from switchgrass bales to deconstruct ammonia-pretreated switchgrass (DSG). Correlation analysis was carried out to elucidate the relationship between microbial decomposition of DSG by these communities, enzymatic activities produced and enzymatic saccharification of DSG using these enzyme mixtures. Results of the analysis showed that ß-glucosidase and xylosidase activities limited the extent of microbial deconstruction and enzymatic saccharification of DSG. The results also underlined the importance of ligninase activity for the enzymatic saccharification of pretreated lignocellulosic feedstock. The bacterial-fungal communities developed in this research can be used to produce enzyme mixtures to deconstruct DSG, and the results from the correlation analysis can be used to optimize these enzyme mixtures for efficient saccharification of DSG to produce second-generation biofuels.
Asunto(s)
Amoníaco/metabolismo , Bacterias/metabolismo , Enzimas/metabolismo , Hongos/metabolismo , Panicum/metabolismo , Biocombustibles/microbiología , Biomasa , Electroforesis en Gel de Gradiente Desnaturalizante , Reacción en Cadena de la Polimerasa , Análisis de Componente Principal , TemperaturaRESUMEN
Despite multiple research efforts, the current strategies for exploitation of lignocellulosic plant matter are still far from optimal, being hampered mostly by the difficulty of degrading the recalcitrant parts. An interesting approach is to use lignocellulose-degrading microbial communities by using different environmental sources of microbial inocula. However, it remains unclear whether the inoculum source matters for the degradation process. Here, we addressed this question by verifying the lignocellulose degradation potential of wheat (Triticum aestivum) straw by microbial consortia generated from three different microbial inoculum sources, i.e., forest soil, canal sediment and decaying wood. We selected these consortia through ten sequential-batch enrichments by dilution-to-stimulation using wheat straw as the sole carbon source. We monitored the changes in microbial composition and abundance, as well as their associated degradation capacity and enzymatic activities. Overall, the microbial consortia developed well on the substrate, with progressively-decreasing net average generation times. Each final consortium encompassed bacterial/fungal communities that were distinct in composition but functionally similar, as they all revealed high substrate degradation activities. However, we did find significant differences in the metabolic diversities per consortium: in wood-derived consortia cellobiohydrolases prevailed, in soil-derived ones ß-glucosidases, and in sediment-derived ones several activities. Isolates recovered from the consortia showed considerable metabolic diversities across the consortia. This confirmed that, although the overall lignocellulose degradation was similar, each consortium had a unique enzyme activity pattern. Clearly, inoculum source was the key determinant of the composition of the final microbial degrader consortia, yet with varying enzyme activities. Hence, in accord with Beyerinck's, "everything is everywhere, the environment selects" the source determines consortium composition.
Asunto(s)
Bacterias/metabolismo , Celulasas/metabolismo , Celulosa 1,4-beta-Celobiosidasa/metabolismo , Hongos/metabolismo , Lignina/metabolismo , Consorcios Microbianos , Triticum/metabolismo , Bacterias/enzimología , Bacterias/genética , Hongos/enzimología , Hongos/genética , ARN Ribosómico 16S/genética , Microbiología del SueloRESUMEN
Fungi, particularly aquatic hyphomycetes, have been recognized as playing a dominant role in microbial decomposition of plant litter in streams. In this study, we used a microcosm experiment with different levels of fungal diversity (species number and identity) using monocultures and combinations with up to five aquatic hyphomycete species (Articulospora tetracladia, Tricladium splendens, Heliscus submersus, Tetrachaetum elegans and Flagellospora curta) to assess the effects of ethanol and phenanthrene on three functional measures: plant litter decomposition, fungal biomass accrual and reproduction. Alder leaves were conditioned by fungi for 7days and then were exposed to phenanthrene (1mgL(-1)) dissolved in ethanol (0.1% final concentration) or ethanol (at the concentration used to solubilise phenanthrene) for further 24days. Exposure to ethanol alone or in combination with phenanthrene decreased leaf decomposition and fungal reproduction, but increased fungal biomass produced. All aspects of fungal activity varied with species number. Fungal activity in polycultures was generally higher than that expected from the sum of the weighted performances of participating species in monoculture, suggesting complementarity between species. However, the activity of fungi in polycultures did not exceed the activity of the most productive species either in the absence or presence of ethanol alone or with phenanthrene.
Asunto(s)
Alnus/microbiología , Etanol/efectos adversos , Hongos/efectos de los fármacos , Hongos Mitospóricos/efectos de los fármacos , Fenantrenos/efectos adversos , Hojas de la Planta/microbiología , Ríos/microbiología , Biomasa , EcosistemaRESUMEN
Here, we investigated how different plant biomass, and-for one substrate-pH, drive the composition of degrader microbial consortia. We bred such consortia from forest soil, incubated along nine aerobic sequential - batch enrichments with wheat straw (WS1, pH 7.2; WS2, pH 9.0), switchgrass (SG, pH 7.2), and corn stover (CS, pH 7.2) as carbon sources. Lignocellulosic compounds (lignin, cellulose and xylan) were best degraded in treatment SG, followed by CS, WS1 and WS2. In terms of composition, the consortia became relatively stable after transfers 4 to 6, as evidenced by PCR-DGGE profiles obtained from each consortium DNA. The final consortia differed by ~40 % (bacteria) and ~60 % (fungi) across treatments. A 'core' community represented by 5/16 (bacteria) and 3/14 (fungi) bands was discerned, next to a variable part. The composition of the final microbial consortia was strongly driven by the substrate, as taxonomically-diverse consortia appeared in the different substrate treatments, but not in the (WS) different pH one. Biodegradative strains affiliated to Sphingobacterium kitahiroshimense, Raoultella terrigena, Pseudomonas putida, Stenotrophomonas rhizophila (bacteria), Coniochaeta ligniaria and Acremonium sp. (fungi) were recovered in at least three treatments, whereas strains affiliated to Delftia tsuruhatensis, Paenibacillus xylanexedens, Sanguibacter inulus and Comamonas jiangduensis were treatment-specific.
Asunto(s)
Bacterias/metabolismo , Hongos/metabolismo , Lignina/metabolismo , Consorcios Microbianos , Plantas/microbiología , Microbiología del Suelo , Bacterias/clasificación , Bacterias/genética , Bacterias/aislamiento & purificación , Biomasa , Hongos/clasificación , Hongos/genética , Hongos/aislamiento & purificación , Filogenia , Plantas/clasificaciónRESUMEN
Two different biomasses were subjected to simultaneous pretreatment and saccharification (SPS) using a cocktail of hydrolytic and oxidizing enzymes. Application of a novel laccase as a detoxifying agent caused the removal of 49.8% and 32.6% of phenolic contents from the soaked rice straw and willow, respectively. Hydrolysis of soaked substrates using a newly developed fungal consortium resulted in saccharification yield of up to 74.2% and 63.6% for rice straw and willow, respectively. A high saccharification yield was obtained with soaked rice straw and willow without using any hazardous chemicals. The efficiency of each step related to SPS was confirmed by atomic force microscopy. The suitability of the developed SPS process was further confirmed by converting the hydrolysate from the process into bioethanol with 72.4% sugar conversion efficiency. To the best of our knowledge, this is the first report on the development of a less tedious, single-pot, and eco-friendly SPS methodology.